Cableheads are used to connect support members such as cables, including wireline or slickline, composite cables, tubulars or rods to toolstrings. The cablehead provides the interface, both mechanical and in some cases electrical between the support member and the toolstring.
Conventional cableheads are known, however, these devices have drawbacks which, in some cases, decrease their utility. For example, it is known to provide a cablehead in which the grip increases as the load on the support member is increased. However these devices are only suitable for increasing the load in a single direction. If the load is increased in the opposite direction, the grip on the support member can be lost and, for example, the toolstring may be released from the support member to fall downhole.
Furthermore, a problem known in conventional devices is migration of gas through the cablehead which can lead to short circuit of electrical connections.
Conventional cableheads have to be assembled with great care to prevent damage to the support member. Over tightening a cablehead can crush the cable such that wires in the cable, for example, short circuit.